These .debs for tn5250 and x5250 were built using checkinstall so won't do proper dependency checking. I'd recommend installalling the tn5250 package from your distribution's repositories first, un-installing it and then installing these.
x5250 built on Ubuntu 9.10
This should install over tn5250-0.17.4-2 that's in Ubuntu (and likely the 0.17.3-2 in Debian Lenny)